Axial flow turbo compressor



June s, 1939. c. KELLER 2,161,517

AXIAL FLOW TURBO COMPRESSOR I Filed Sept. 21, 1937 v 2 Sheets-Sheet l Zinnentor M'Mm attorneys June 6, 1939.

c. KELLER 2,161,517

AXIAL FLOW TURBO COMPRESSOR Filed Sept. 21, 1937 110 6 Iic 3n ventor' @JIMJMM Gttornegs '2 Sheets-Sheet 2 Patented June 6, 1939 UNITED STATES AXIAL FLOW TURBO COMPRESSOR Curt Keller, Zurich, Switzerland, assignor to Escher Wyss Machinenfabriken Aktiengesellschaft, Zurich, Switzerland, a corporation of Switzerland Application September 21, 1937, Serial-No. 164,954 In Switzerland October 26, '1936 6 Claims. '(Cl. 230-119) This invention relates to multistage axial. flow turbo-compressors with one or more casings and at least one external, intermediate cooler. The principal object of the invention is to permit the use of intermediate coolers with axial fiow turbocompressors without the energy losses which have heretofore been inherent in such an arrangement.

It has long been considered desirable to operate 9 gas compressors in such manner as to obtain so nearly as possible an isothermal compression, for the reason that under certain pressure conditions the energy absorbed by the compressor is then a minimum. The familiar mode of securing \the desired result is to useintermediate coolers either between successive single stages or between successive groups of stages. By increasing the number of. intermediate coolers, an isothermal compression can be closely approached, but

there is an economic limit to the number of inter coolers because of energy losses at the inlet and outlet of the coolers, as well as throughout the connections to and from the coolers.

The problem is particularly diflicult in a multistage axial flow turbo-compressor, because in passing from a stage or group of stages to the intercooler, the direction of flow must change from axial to substantially radial. Such deflection can be effected by the use of curved ducts or casings, but this solution of the problem is attended by the disadvantage that much valuable space is consumed. Furthermore, there are serious energy losses because in an axialflow compressor the velocities of flow are high as compared with the peripheral velocity of the wheel.

The present invention overcomes the above difficulty by causing the stage or group of stages of the axial flow turbo-compressor todeliver to an auxiliary centrifugal wheel deflecting the axial through-flow into the supply conduit leading to the intermediate cooler. Thus, the change in direction of flow takes place with the performance of work by the auxiliary centrifugal Wheel, but only to the extent as is necessary for a deflection in the small possible space.

The auxiliary wheel imparts a rotary motion tb the medium undergoing compression, such rotary motion occurring in a plane which is normal or approximately normal to the axis of the compressbr shaft. This rotary motion is partially .converted into pressure in the conduit leading to the intermediate cooler, such conduit being suitably designed for the purpose, as a special casing acting as a diffuser. Since the auxiliary centrifugal wheel receives the medium from' the .pre-

ceding axial flow stages at a high inlet velocity, the auxiliary wheel operates with good efficiency so that the transition from the axial flowcompressor to the intermediate cooler occurs with little or no energy loss. Consequently, the invention not only economizes space as compared to. the/prior'art, but reduces the energy losses to a very small amount.

It is recognized that multistage turbo-compressors made up of axial flow and radial flow wheels, either in one or separate casings are lmown. These prior art devices however had nothing to do with inter-cooling, but usually sought totake advantage of the superiority of the axial flow wheels in the ranges in which the pressures were low and the volumes large, while securing the advantages of the radial flow wheels in the high pressure range, i.- e., in that range in which the density of the medium wasrelatively great. This construction is known toafford economy of space, particularly because the axial stages do not require any room for large radial diffusers. Suchconstruction involves no recogni-' tion of the problem of the'intercooler, with which device the medium must pass outside the casing of the compressors to the intercooler and then be returned to the casing.

It has also been proposed to. use axial and radial flow stages in alternation, but here the axial flow type of turbo-compressors to economical operation with intermediate coolers.

Preferred embodiments of the invention are shown in the accompanying drawings, in which- Fig. l is a view, part in elevation and part in longitudinal section, of an axial flow turbocompressor, having a single casing and having two intermediate coolers with associated radial flow wheels.

Fig. 2 is a section on the line 2-2 of Fig. 1.

Fig. 3 is an end view of the compressor of Fig. 1 as viewed from the left in that figure.

Fig. '4- is a view similar to Fig. 1 and showing a modification in-which separate casings are used for different groups of stages.

' Fig. 5 is a view similar to the right hand portion of Fig. 4 and showing a possible further motor 9 through shaft H and carries blades I2,

. cooler 28 (identical with cooler 22).

or the equivalent, which turn between stationary guide blades l3 or the equivalent in the housing, the guides l3 and blades l2 being designed for axial flow. The inlet or suction connection is indicated at H and the discharge or pressure connection at l5.

Contrary to the usual construction the blades just mentioned are divided into three groups A, B and C by the interposition of radial flow, i. e., centrifugal runners l6 and I! with associated diffuser housings I8 and I9. These are identical except that they differ in dimensions to correspond to the different stages of compression.

The auxiliary centrifugal wheel l6 receives from group A and deflects the axial through-flow into the spiral diffuser housing [8 which delivers through duct 2| to the conventional multitubular cooler 22, in which the compressed gas flows through the tubes and cooling fluid (water) flows around the tubes. shown at 23, 24. From intercooler 22 the cooled gas 'flows by curving pipe 25 to the inlet ring 26 of group B. I

The auxiliary centrifugal wheel ll receives compressed gas from group B and deflects the axial through-flow into the spiral diffuser housing l9 which delivers through duct 21 to inter- From cooler 28 flow 'is by pipe 29 'to the inlet ring 3| of group C.

In this way a compact and highly emcient structure is provided. The auxiliary radial flow wheels l6, 11 provide for the necessary deflection of the axial through-flow in a very small space and with the smallest possible loss. Since the centrifugal wheels l6 and i1 impart rotary movement to the gas undergoing compression, the housings l8 and is are designed for atleast a part of their extent as spiral casings serving as diffusers.

If desired conventional difiusers may be inter-' .groups B and C stages (runner; 8b) are in a separate housing lib, lb. Other parts corresponding to parts in Fig. 1 are given the same refermice numbers with the letter a.

'Fig. 5 shows a unit identical with the right hand unit in Fig. 4 except that the heel I60, un-

designed to receive the oblique discharge. This structure is shown to indicate that the desired action can be had without adherence to the use of strictly radial wheels for diverting and controlling flow through the intercoolers.

Several modifications have. been described for illustrative purposes and others are possible within the scope of the invention.

What is claimed is I 1. A turbo-compressor comprising two groups ot'axial flow stages;- an intercooler for cooling comprwed working medium; a radial flow wheel coaxial with said turbo-compressor betweeen said groups and arranged to receive working medium Water connections are i compressed in the first group and deliver it with change of direction to said intercooler with performance of work approximately to the extent necessary for deflection; and a connection for conducting working medium from the intercooler to said second group.

2. A turbo-compressor. comprising two group of axial flow stages; an intercooler for cooling compressed Working medium; a radial flow unit arranged coaxially with said axial flow stages and so as to receive medium compressed by the first group of stages, said radial unit including a radial flow wheel and coacting spiral casing arranged to act as a diffuser and deliver medium leaving theradial wheel to the intercooler, the wheel and easing being so designed that the change in wheel turning with said runner within said hous-- ing, the radial flow wheel being so designed as to receive medium from the first of said successive stages, deflect it from its axial path, and deliver it to said intercooler with performance of work approximately. to the extent necessary for deflection.

4. The combination of a multi-stage axial flow turbo-compressor including a housing and a run: ner, and having at least one intercooler interposed between two successive stages; and a flow diverting unit comprising a radial flow wheel turning with said runner within a portion of said housing formed as a diffuser, the parts being so designed that the radial flow wheel receives working medium from the first of said successive stages, and deflects it through said difiuser to said intercooler with performance of work approximately to the extent necessary for deflection.

5. The combination of a multi-stage axial flow turbo-compressor including a housing and a runner and having at least one intercooler interposed between two successive stages; and means for guiding working medium flowing from the first of said successive stages from its axial path to said intercooler without substantial loss of energy, said means comprising a radial flow wheel turning coaxially with said runner, and so designed .as to perform substantially the minimum work consistent with efficient deflection of the working medium from its axial path.

6. The combination of a multi-stage axial flow turbo-compressor including a housing and a run- 'ner and having at least one intercooler interposed between two successive stages; and means for guiding working medium flowing from the first of said successive stages from its axial path to said, intercooler without substantial loss of energy, said means comprising a radial flow wheel turningcoaxially with said runner, and a housing for said radial flow wheel, said housing serving as a difiuser toconvert velocity head of medium leaving the radial wheel into pressure as the medium approaches the intercooler, and the radialflow wheel being so designed as to perform substantially the minimum .work consistent with effective deflection of the working medium from 

